1. Field of the invention
This invention relates to an image stabilization apparatus for preventing an image vibration on the imaging plane in a camera or the like caused by hand vibration or the like.
2. Related Background Art
As the image stabilization apparatus as described above, mention may be made of an apparatus covered, for example, in the applicant's U.S. application Ser. No. 280,731. This apparatus is such that a correcting optical system for correcting image vibration is displaced in a plane substantially perpendicular to the photographing optic axis in a direction to compensate any image vibration on the imaging plane, i.e., the direction opposite to the direction of image vibration, to thereby prevent the image on the imaging plane from vibrating. Therefore, in this apparatus, two parallelogrammatic links each having a degree of freedom are series-connected so that their degrees of freedom are perpendicular to each other in a plane substantially perpendicular to said photographing optic axis, and said correcting optical system is held at the end thereof, whereby said correcting optical system becomes displaceable in the plane substantially perpendicular to the photographing optic axis in the direction opposite to the direction in which the image on the imaging plane vibrates, and said parallelogrammatic links are elastically urged against a cam, which is driven by a motor so as to displace the correcting optical system in the direction opposite to the direction of vibration, thereby preventing image vibration on the imaging plane.
Thus, in order to correct image vibration, it is necessary to displace the correcting optical system, but the amount by which the correcting optical system can be displaced is limited, and for example, in the case of the above-described apparatus, the cam is a snail cam and therefore, when the cam moves to a position beyond the terminal position, i.e., the minimum or maximum lift position, the correcting optical system returns to the start/end position, i.e., the maximum or minimum lift position, of the cam, and this has led to the problem that the direction of displacement is reversed to the same direction as the direction of image vibration to increase image vibration.
Also, where the optical instrument in which image vibration is to be prevented has a great vibration acceleration or where the optical instrument tries to recover from the error of velocity or displacement attributable to the unevenness of the cam surface the motor tries to produce a great acceleration, but in this case, there has been the problem that said correcting optical system becomes unable to follow the movement of the motor and the cam for driving the correcting optical system, whereby the image stabilization action cannot be accomplished.